A bioassay-guided separation protocol, including the testing of the extracts, fractions and pure compounds for their ability to inhibit P-glycoprotein (the efflux pump responsible for the multidrug resistance of the used cell line) of mouse lymphoma cells containing the human efflux pump gene MDR1, led to the isolation of seven compounds from the chloroform and ethyl acetate soluble fractions of the methanolic extract of Carpobrotus edulis. The compounds were identified by 1D, 2D NMR and MS investigations as triterpens (beta-amyrin, uvaol and oleanolic acid), monogalactosyldiacylglycerol, catechin, epicatechin and procyanidin B5. Uvaol was the most effective and promising compound in the reversal of multidrug resistance in MDR mouse lymphoma cell line.